The answer to 'furnace repair blowing cold air' is that your furnace is likely not functioning properly and needs repair. Some common causes include a malfunctioning thermostat, a problem with the pilot light or ignition system, a clogged air filter, or issues with the blower motor or fan. Symptoms may include the furnace running but only blowing cold air, or the furnace not turning on at all.
If your furnace is blowing cold air, the first step is to check the thermostat and make sure it is set to 'heat' and the temperature is set higher than the current room temperature. You can also try replacing the air filter. However, if these simple fixes don't resolve the issue, it's best to call in a professional HVAC technician to diagnose and repair the problem. Attempting complex furnace repairs without the proper expertise can be dangerous and may end up causing more damage.